Pune Police Commissioner Gulab Rao Pol described the explosions as an act of mischief but Union Home Secretary RK Singh said terror angle cannot be ruled out since it seems to be a planned attack.

A man allegedly carrying one of the bombs was injured in the explosions and has been taken into custody and is being interrogated, Singh said. He has been admitted to a local hospital.

Explosive in cake box

Pol said the explosives carried by the injured man was kept in a cake box with sticky material, two detonators and a pencil cell. One detonator went off in the explosion while the second was defused by a bomb disposal squad team.

Sushilkumar Shinde, who took over as Union Home Minister on Wednesday, was due to have visited the city on Wednesday evening but the trip was cancelled. Ironically, his last two days in the Power ministry was marked by a major power outage due to collapse of three grids.

He parried questions in Delhi on whether it was a terror attack, saying they were minor explosions and a probe was on into the blast that occurred between 7.27 pm and 8.15 pm.

Pune was rocked by a bomb blast at German Bakery in February 2010 in which 15 people were killed.

Explosions at Balgandharva Theatre

The explosions occurred at Jangli Maharaj(JM) road at spots near Balgandharva Theatre, Dena Bank branch, a McDonald food outlet and Garware bridge. The first explosion went off at Balgandharva Theatre where the suspected bomber was injured.

The explosion outside McDonald went off in a dustbin while the blasts near Garware bridge and Dena bank were reported from a cycle which had a bucket with explosives strapped on, police said.

The entire JM Road area has been cordoned off. Pol said explosives at one of the sites was kept in a polythene bag.

Maharashtra ATS rushes to spots

Maharashtra ATS and Bomb Detection and Disposal Squads were at the spots, police said.

Asked if it was a terror attack, Maharashtra DGP Sanjeev Dayal said, "It is not appropriate to comment at this moment. Police teams have reached the spot and are looking into the matter."

Maharashtra Additional DG (Law & Order) Satyapal Singh said, "The first explosion near Balgandharva Theatre occurred at 19.27 hours and the rest followed afterwards though the exact timings are not yet clear, while one cyclist was injured".

Singh said he had no information about any fifth explosive device being found and defused.

Pol said, "All are minor explosions. The public need not panic. Police are alert and they are doing their job."

"The bombs went off between 7.27 pm and 8.15 pm. One person has been injured. He is admitted at Sassoon hospital. Police is recording his statement. These blasts were of low intensity," Shinde said.

NIA teams have been sent to Pune: Shinde

Shinde said teams of National Investigation Agency (NIA) and a bomb disposal squad of National Security Guards(NSG) have been rushed to Pune.

"I was planned to go to Pune at 6 pm on Wednesday to attend a function of 'Lokmanya Tilak Prize' at Tilak theatre there. I have no information of being a terror attack," he added.

"There were four low intensity bombs in which one person was injured. Terror angle cannot be ruled out as it appears that it was a planned attack," Union Home Secretary R K Singh said.

"One person who allegedly carrying one of the bombs in a bag was injured and he has been taken into custody. His interrogation is going on," he added.

RR Patil reviews the security situation

Maharashtra Home Minister RR Patil on Wednesday reviewed the security situation in the state with senior officials.

Patil discussed the situation with top Home Department officials, sources said. An alert has been issued following the explosions, which come a day ahead of the Raksha Bandhan festivities.

Strict vigil at railway, bus stations, malls, markets, lodges

A strict vigil will be maintained at crowded places like railway and bus stations, malls, markets and lodges, a Home Department official said.

Police said the injured person was identified as Dayanand Patil. Patil suffered injuries in his stomach, police added.

Volunteers of Anna Hazare's anti-corruption movement were holding protests near the site of the first explosion at Balgandharva theatre.

Police said blasts near Dena bank and Garware Bridge underpass left the wire-meshed carrier bags, attached to the front of the bicycles, in which the explosive material was put, shattered. The blast that occurred near McDonald's was of the explosive kept in a dustbin at its outer gate.

Pol said a small live detonator found at Balgandharva blast site was later defused by bomb squad. Eyewitnesses said the explosions sounded like Diwali fire crackers as people ran helter-skelter. Life in the city returned to normal after the initial scare and traffic flow was gradually restored.

Meanwhile, reacting to the explosions, Maharashtra Chief Minister Prithviraj Chavan said a thorough probe would be conducted and all efforts would be made to find the culprits.

He said teams of NIA and NSG have been sent to Pune to probe the blasts. "We are closely monitoring the situation," Chavan said.